Founded in 2008, Celsus Group provides locum doctors and nurses to healthcare providers including GP surgeries, hospitals, urgent treatment centres, telemedicine providers, and to a lesser extent, non-healthcare providers such as prisons and the MoD. The Celsus Group is formed of Medical Staffing, Key Medical Services, 111 Lifeline and TNA Medical.
Souter Investments was part of a Sullivan Street led syndicate that invested in Celsus in March 2020. The investment thesis was to deliver organic growth via capitalising on labour shortages and increased demand for medical professionals necessitating the need for locum staffing.
In January 2025, Celsus was sold to a trade player for an undisclosed price.